Online presentation broadcast technology allows people to “attend” a virtual presentation broadcast by broadcasting the presentation over a network to computers that are accessible to the attendees. Recent advancements in networking and online presentation broadcasting technology have led to a rapid increase in the use of such virtual presentation broadcasts, particularly over intranets within large corporations. Of course, the advantages of virtual presentation broadcasts are perhaps best realized over the Internet, which can reach an even greater audience. While these advancements have been dramatic, the ease of use in presenting and receiving such broadcasts have not kept pace.
A typical online broadcast of a presentation is performed in the following manner. A presentation designer, or design team, creates a presentation, which typically comprises a plurality of slides, including text and/or graphic content. The presenter then conducts a “live” performance of the presentation, which is recorded using one or more video cameras with microphones. The recorded presentation generally consists of video and audio content that is recorded on a magnetic tape media using an analog encoding format. For example, conventional television signals are encoded using one of three standard formats: National Television System Committee (NTSC—used in North America), Phase Alternating Line (PAL), or Sequential Color and Memory (SECAM). These standards define encoding schemes for mechanisms that can be used to encode and/or decode analog audio and video broadcasts or tape recordings. For instance, a camcorder designed for use in the United States will encode video and audio content using the NTSC analog format, so that the recorded video and audio content can be viewed on a conventional television when it is played on the camcorder (or other playback equipment).
Although the foregoing analog recording technology and encoding formats have worked well for many years, recordings that use these formats cannot be directly used to transmit audio and/or video content via an online broadcast, since computer networks cannot transfer content that is in an analog format. This problem is addressed by using special audio and video “capture” equipment, which converts the analog signals produced by audio and video recording (and broadcasting) equipment into a digital format, using a special type of encoding scheme and/or device called a codec. The term codec, which is an abbreviated form of coder/decoder, actually originated in the field of analog communications. NTSC, PAL, and SECAM are examples of analog codecs used in television broadcasting.
Through use of one or more codecs, the capture equipment converts an analog recording (or original broadcast signal) into a digital format in the following manner. Typically, the recording is converted into a digital format by using a computer that includes one or more audio and/or video capture cards that receive an analog signal produced by the playback equipment (or which is directly produced by equipment such as a microphone or television broadcast camera) during the live presentation and converts it into a digital format using a particular codec that the cards are designed to implement. Such cards generally employ a special chip that is programmed with logic for converting an input analog signal to an encoded digital signal of a predetermined format, preferably in real-time.
Under Microsoft Corporation's WINDOWS™ operating systems, codecs are usually implemented to be ACM (Audio Compression Manager) or VCM (Video Compression Manager) compatible, so that the output of the codecs can be directly read and used by ACM and VCM compatible software. Various ACM and VCM compatible codecs are used to produce audio and/or video content in several different formats, including file formats related to the extensions .wav, .avi, and .mov, as well as MPEG and MP3 formats.
Once the audio and/or video content of the presentation is converted into an appropriate digital format, it can be sent to an online audience. In the past, this task has been done after a request from each audience member causes the file or files comprising the content of the presentation to be downloaded to their own computers. Once the file is downloaded, the presentation can be viewed by “playing” the file with an appropriate codec player, such as Microsoft Corporation's WINDOWS MEDIA PLAYER™, or the QUICKTIME™ player developed by the Apple Computer Corporation. In order to view a presentation in this manner, it is necessary that the appropriate player be already installed on the viewer's computer.
In addition to viewing presentations in the foregoing manner, recent advancements in streaming format technology have made it possible to receive audio and video content via live broadcasts over the Internet and other network environments. As opposed to conventional network file transfer schemes, streaming format technology allows content to be continuously “streamed” to one or more computers over a network rather than being first downloaded as a file. A typical example illustrating the use of streaming format technology is a live Internet concert, in which audio and video equipment at the performance site produce signals that are converted into a digital format in real- or near real-time (or are already in a digital format if digital camera equipment is used), and the digital content is converted into an appropriate streaming format and broadcast to a large audience accessing the concert via an Internet Web page. In addition to concerts, streaming technology is presently used for broadcasting other types of live events, including presentations.
Although the foregoing schemes have greatly advanced the use of online broadcasting, they have significant drawbacks when they are used for broadcasting an online presentation. Notably, when employing either of these methods, the screen area occupied by the video image seen by the online audience is quite small, often making the content of the presentation, especially presentation slides, difficult to view. The relatively small size of the video image is generally due to bandwidth and compression technology limitations, as well as quality considerations. For example, a video frame update rate of 30 frames per second (fps) is generally believed to be the minimum acceptable frame rate for rendering objects that move at a medium rate of motion, such as a person giving a live presentation. In addition, 30 fps is the accepted rate in the NTSC television standard, so most people are accustomed to viewing video content at this frame rate. Suppose the maximum bandwidth connection available to a person in the audience viewing a presentation is 28.8 Kilobits per second (Kbps). In order to maintain a frame rate of 30 fps under this data bandwidth, the video content and audio content of the presentation should be divided into 22 Kbps and 6 Kbps portions, respectively. Under Microsoft Corporation's WINDOWS™ media technology, the 22 Kbps video content portion corresponds to a 22 Kilobit WINDOWS™ media encoder template that produces a video image of only 160×120 pixels, while the audio content portion is encoded by an appropriate codec as a monophonic audio signal at 6 Kbps (corresponding to a sampling rate of 8 KHz). When displayed on many of today's computer monitors, which typically provide a display resolution of 1024×768 pixels or greater, a video image of 160×120 pixels only occupies a small portion of the monitor's available display area. Therefore, a presentation slide that was originally intended to use a monitor's entire display area will be difficult, if not impossible, to be clearly viewed or read on the recipient's monitor. Accordingly, a live presentation broadcast that produces such a small video image will be of little value to most audience members.
A similar problem exists when viewing a presentation that is enabled through the use of downloaded files. In order to conserve file size, as well as for other reasons, the display area of an image in a video media player is again generally only a fraction of the total display area of a monitor. As a result, this method also does not adequately display presentation slide images.
Although online broadcasting of live events such as presentations allows an audience to attend the event from remote locations, other people who would like to attend the presentation (either in person or remotely) may be prevented from doing so because of scheduling conflicts. Accordingly, it would be advantageous to enable such people to view the presentation at a later time, preferably when their schedule permits. As discussed above, content corresponding to the live portion of the event (e.g., presentation) can be captured and encoded into a streaming format and broadcast over a network to a remote audience. In addition, the live content of the event can be recorded for later playback by simply saving the data stream produced by the encoder to a file as it is produced. The recorded content file can then be distributed to end users via a network transfer of the file or a physical distribution of the file on a CD-ROM or floppy disk. The live content can then be replicated on a viewer's computer by simply playing back the file using a suitable multimedia player. Internet news services frequently employ this scheme by using playback files that can be downloaded and played to replicate live content, such as the audio portion of a reporter's interview, or replay of an important portion of a news or sporting event.
This scheme works well for recording and replicating most live events. However, since presentations generally include a slide show content comprising a plurality of presentation slides in addition to live content, it is desirable to replicate both the slide show content and the live content in a manner that enables the viewer to perceive the full content of the original presentation. Ideally, an acceptable solution to this problem should produce a composite display image comprising a portion of a viewer's display screen on which visual aspects of a live presentation are replicated, and another (preferably larger) portion of the display screen on which the slide show content is replicated, thereby enabling the viewer to clearly see the presentation slides. At the same time, the system should replicate the audio content of the presentation through the viewer computer's sound system, and the audio, video, and slide show content should all be synchronized, just as in the original presentation.
At present, there is no automated scheme for producing this result. Using conventional methods, this result is achieved by manually adding synchronization calls for displaying and/or animating the various slides in the slide show and linking to the various slide image source files. This manual process is rather tedious and prone to error. Accordingly, it would be desirable to provide an automated method for embedding the synchronization calls and links in the streaming format file so that when the file is played, the full content of the live presentation is replicated in synchrony just as in the original presentation.
Another problem with the prior art scheme is that the links to the slide files typically are absolute, such as a URL address in the form “http://<network domain><directory path>/slidename.” A drawback of this scheme is that it makes it difficult to move slide files and streaming files corresponding to an archived recording of a presentation. If the files are moved, all of the links have to be updated. Accordingly, it would be advantageous to provide a scheme that allows the recording files to be moved without requiring that the embedded links be updated.